<template>
	<div>
		<canvas id="s-canvas" :width="contentWidth" :height="contentHeight"></canvas>
	</div>
</template>

<script>
	export default {
		name: 'identify',
		props: {
			identifyCode: {
				type: String,
				default: '1234'
			},
			fontSizeMin: {
				type: Number,
				default: 16
			},
			fontSizeMax: {
				type: Number,
				default: 40
			},
			backgroundColorMin: {
				type: Number,
				default: 200
			},
			backgroundColorMax: {
				type: Number,
				default: 300
			},
			colorMin: {
				type: Number,
				default: 50
			},
			colorMax: {
				type: Number,
				default: 160
			},
			lineColorMin: {
				type: Number,
				default: 30
			},
			lineColorMax: {
				type: Number,
				default: 300
			},
			dotColorMin: {
				type: Number,
				default: 0
			},
			dotColorMax: {
				type: Number,
				default: 255
			},
			contentWidth: {
				type: Number,
				default: 120
			},
			contentHeight: {
				type: Number,
				default: 40
			}
		},
		methods: {
			// 生成一个随机数
			randomNum(min, max) {
				return Math.floor(Math.random() * (max - min) + min)
			},
			// 生成一个随机的颜色
			randomColor(min, max) {
				let r = this.randomNum(min, max)
				let g = this.randomNum(min, max)
				let b = this.randomNum(min, max)
				return 'rgb(' + r + ',' + g + ',' + b + ')'
			},
			drawPic() {
				let canvas = document.getElementById('s-canvas')
				let ctx = canvas.getContext('2d')
				ctx.textBaseline = 'bottom'
				// 绘制背景
				ctx.fillStyle = this.randomColor(this.backgroundColorMin, this.backgroundColorMax)
				ctx.fillRect(0, 0, this.contentWidth, this.contentHeight)
				// 绘制文字
				for (let i = 0; i < this.identifyCode.length; i++) {
					this.drawText(ctx, this.identifyCode[i], i)
				}
				this.drawLine(ctx)
				this.drawDot(ctx)
			},
			drawText(ctx, txt, i) {
				ctx.fillStyle = this.randomColor(this.colorMin, this.colorMax)
				ctx.font = this.randomNum(this.fontSizeMin, this.fontSizeMax) + 'px SimHei'
				let x = (i + 1) * (this.contentWidth / (this.identifyCode.length + 1))
				let y = this.randomNum(this.fontSizeMax, this.contentHeight - 5)
				var deg = this.randomNum(-20, 20)
				// 修改坐标原点和旋转角度
				ctx.translate(x, y)
				ctx.rotate(deg * Math.PI / 180)
				ctx.fillText(txt, 0, 0)
				// 恢复坐标原点和旋转角度
				ctx.rotate(-deg * Math.PI / 180)
				ctx.translate(-x, -y)
			},
			drawLine(ctx) {
				// 绘制干扰线
				for (let i = 0; i < 8; i++) {
					ctx.strokeStyle = this.randomColor(this.lineColorMin, this.lineColorMax)
					ctx.beginPath()
					ctx.moveTo(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight))
					ctx.lineTo(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight))
					ctx.stroke()
				}
			},
			drawDot(ctx) {
				// 绘制干扰点
				for (let i = 0; i < 80; i++) {
					ctx.fillStyle = this.randomColor(0, 255)
					ctx.beginPath()
					ctx.arc(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight), 1, 0, 2 * Math.PI)
					ctx.fill()
				}
			}
		},
		watch: {
			identifyCode() {
				this.drawPic()
			}
		},
		mounted() {
			this.drawPic()

		}
	}
</script>
